1. Field of the Invention
The present device pertains to video amplifiers. Specifically, the present device pertains to video amplifiers which are clocked at a sampling rate suitable for use with charge coupled devices.
2. Description of the Prior Art
Charge coupled devices, CCDs, have become a new electronic device for securing and transmitting video images. They are also known as bucket brigade devices. The fundamental principle of a CCD camera is to focus a field of view on a charge coupled device array of pixels. The number of pixels in the area provides a direct control over the quality of the picture. In general, the scene is integrated in a set time and then all pixels are read out to form a composite image. Previous devices have relied on bandpass filters to limit the amount of noise that is transmitted in the processing signal.
FIG. 1 shows a typical integration chart of amplitude versus time for a given pixel of a charge coupled device. The sharp lines between the jagged irregular saw teeth represent noise spikes. The time period for these noise spikes is very brief. The corresponding frequency of these short time periods, the inverse of the time period, causes processing techniques to center on filtering out high frequency components of the video signal. In general, high frequency components have been considered spurious information and therefore were not preserved in processing hierarchy because they permitted large amounts of noise to be processed with the signal. Prior art devices have had bandpass filters with cutoffs of approximately 1.5 MHz to 6 MHz.
The expansion of pixel arrays to larger and larger numbers of elements provides improved imaging for charge coupled device, CCD, cameras. For high level processing, sharp edges can be used for automatic video readout. To enhance sharp edges it is preferred to keep high frequencies in the video signal. High frequencies define the sharpest edges in a signal and their exclusion by bandpass filtering results in a blurring of the edges that are otherwise possible.
Common circuit components include amplifiers, switches, sample and hold circuits and post amplification. However, these particular circuit components have not been previously combined in a manner which permits sampling of charge coupled device information suitable for sharp edge enhanced video using high frequency components.